Any word when this will get added to the site? I'm considering using The Window for a game I'm building at the moment, and I'd like to know if I should expect the system to get an official listing soon.

Can you change the system of a game? I'm running a Window game, but it's listed as Miscellaneous.

Sure. Go to your game's "Game Control Panel" (through the Game Profile); change the system there and hit 'save'. Note: The change won't happen instantaneous; it will create a game change request which will then be handled by a member of Staff.